Patent Document 1 (shown below) discloses a control system which performs an engine control using the charging efficiency of the engine as a parameter indicative of the engine load. According to this control system, an engine control parameter, for example, a basic ignition timing is calculated by retrieving a map according to the engine rotational speed and the charging efficiency, and the basic ignition timing is corrected in the transient operating condition of the engine to perform the ignition timing control.